Multi-Zone Induction Inverter Noise Reduction via Common Frequency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Induction heating cookers with multiple zones experience audible noise due to differences in operating frequencies, which existing technologies have not effectively addressed while maintaining individual cooking zone power control.
Innovation Solution
A system and method where multiple induction resonant inverters are supplied from a common DC bus, with a control circuitry that determines a master driving frequency and calculates nominal conduction times for each zone, allowing all resonant inductors to operate at a common switching frequency, thus eliminating audible noise while enabling individual cooking zone power control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If variable operating frequencies are applied to different burners in a multi-burner induction heating cooker, then individual cooking zone power control is achieved, but pan interference noise is generated due to frequency differences among the burners
Solution Approach 1:
The patent merges all cooking zones to operate at a common master driving frequency determined by the master resonant inductor, while using duty cycle modulation to provide individual power control. This combines the frequency synchronization needed to eliminate noise with the independent control needed for versatile cooking zones.
Solution Approach 2:
The patent changes the control parameter from frequency variation to duty cycle modulation. Instead of varying operating frequencies to control power in different zones (which causes noise), the system maintains a common frequency and adjusts power levels by changing the duty cycle of the power switching devices.
2Ease of operation
If different operating frequencies are used among multiple resonant inverters, then individual power control of cooking zones is enabled, but audible noise is generated due to frequency differences
Solution Approach 1:
The patent merges all resonant inverters to operate at a common master driving frequency, eliminating the audible noise caused by frequency differences. Individual power control is maintained through duty cycle modulation of each inverter's power switching device.
Solution Approach 2:
The patent changes the control approach from frequency variation to duty cycle modulation. Power control is achieved by varying the duty cycle ratio of the power switching device conduction time relative to the common period, rather than changing operating frequencies.
3Device complexity
If a common DC bus supplies multiple induction resonant inverters, then circuit simplicity and cost are reduced, but frequency synchronization to eliminate noise must be implemented
Solution Approach 1:
The patent merges all resonant inverters to operate at a common master driving frequency sourced from the master resonant inductor's resonant frequency. This frequency synchronization eliminates audible noise while the common DC bus maintains circuit simplicity and cost-effectiveness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively eliminates audible noise caused by frequency differences among cooking zones while allowing for precise power control of each zone, enhancing the operational efficiency and user experience of induction heating cookers.
Implementation Method 1
a high-frequency power switch such as an IGBT is accordingly used. A prior art publication in the technical field of the invention may be referred to as US2010/243642
Implementation Method 2
The internal resistance of the pan causes heat dissipation due to Joule effect
Implementation Method 3
Resonance therefore occurs while the inductor and the capacitor involve in energy exchange
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to a system and method for operating an induction heating cooker by which audible noise caused by different operating frequencies is overcome while still applying individual cooking zone power control. More particularly, the present invention relates to an induction heating cooker (1) comprising a plurality of resonant inductors (6) in association with induction resonant inverters (2) supplied by a common DC bus in the manner that a multi-zone induction coil system is provided, a power switch driving circuit driving power switching devices (5) associated with said induction resonant inverters (2) and a pan detection circuit for detecting presence of a pan.